I. Technical Field
The present invention relates to an EGR device that recirculates a part of exhaust gas discharged from an engine to an air intake side of the engine.
II. Description of the Related Art
In the engines of the motor vehicles, conventional technology of exhaust gas reciculation (EGR) devices is disclosed in Japanese Patent Applications Laid-Open Publication No. 2004-132180 and No. 2003-278608, in which the devices decrease the generation of nitrogen oxide (NOx) by lowering the combustion temperature due to the suppression of fuel combustion in the engine.
In such conventional EGR devices, as shown in FIG. 7, a part of the exhaust gas is introduced from an engine 02 to an EGR cooler 05 through an exhaust manifold 08, and a part of the rest of the exhaust gas discharged from the EGR cooler 05 is introduced into an intake manifold 08c, which is connected with an intake pipe 08a, through a compressor 03a of a turbocharger 03a and an intercooler 04.
Incidentally, the EGR cooler 05 introduces a part of flowing medium that circulates between the engine 02 and a radiator 06, and it decreases the temperature of the exhaust gas due to heat exchange between the exhaust gas and the flowing medium, similarly to devices of the above Japanese patent applications.
In recent years, the radiators are demanded to have higher cooling performances mainly according to the increase of engine outputs. In order to achieve this demand, the larger radiators might be employed, but it has a limit to increase core sizes of the radiators, allowing for its installation space, its weight, its manufacturing costs and others. Consequently, as shown in FIG. 8, a main radiator 06a and a sub-radiator 06b are arranged in a front and back direction thereof to be connected with each other in parallel to each other, or the main radiator 06a and the sub-radiator 06b are arranged in the front and back direction to be connected with each other in series.